This paper describes microwave power absorption in an insect due to the standing-wave irradiation in free space. A method is presented to obtain the heating potential and total absorbed power in the dielectric sphere having the same electrical characteristics as those of insect. Numerical calculations on the pupae of Tenebrio molitor, which has often been used to investigate the microwave biological effects, are given in the frequency range of 1-20GHz, and the results are also discussed with respect to the exposure locations.
The HF radio wave environment within the ionosphere is mainly formed by solar or terrestrial artificial and natural radio sources. An equipment adaptive to the usual ionosonde which is conducted in HF band every 15 min. routinely has been designed so as to enable the reception of interference outside the time interval to receive the observed wave. Using this equipment, successive variation in signals and interferences was measured and the HF radio wave environment there was observed. This report presents the construction of the modified ionosonde and some interpretations for the observational results.
With the recent growth of home-use VTRs, beat disturbances have been occurred in the VTRs in the high-level electromagnetic field of medium-wave broadcasting. We have conducted an investigation of beat disturbances by using a TEM cell and found the following facts. (1) Medium frequency enters around video head when playing back a VTR. (2) Beat frequency is the difference between medium frequency and color subcarrier in the low frequency range. (3) The level of beat disturbance is proportional to the strength of the electromagnetic field, and it varies in accordance with the placement of the VTR. We have used the cancel-coil method as one solution and could reduce the beat to the level not observable on the TV screen.
To prevent fifth harmonic radiation that leaks from microwave ovens, both problems involving the structure of the vent hole and suppressing leaky waves from the power source line of the magnetron have been experimentally studied and a few ways proposed to eliminate these leaky waves. As to the vent hole, a circular hole of 5 [mm] diameter should be adopted to prevent fifth harmonic leaky waves from microwave ovens, and at the same time, a metallic fan with electromagnetic wave-absorbing sheets attached to its blades should be used to provide ventilation. Second, a new method of winding the wave-absorbing electromagnetic tape around the power source line connected to the magnetron is proposed. This tape, consisting of rubber ferrite backed by metal, is effective in reducing the intensity of a strong spectrum radiated from the power source line by more than 10[dB].
A low noise switching dc-dc converter is presented, which operates with an ordinary bipolar transistor and diode. A new converter is based on the buck converter. By positively taking advantage of the switching transistor out put capactance and the transformer leakage inductance, it is posible to realzed little switching noise. When the "off" state transient response reaches zero voltage across the switch, before the beginning the "on "state, it dose so with approximately zero slope. By comparing the new converter noise level with the ordinary buck converter one, we showed its low noise characteristics of the new converter.
First, an occurrence region of showering arc in breaking silver contacts was made clear in this paper. In this region, the spectra of voltage waveforms of showering arc and the radio noise E (dB) caused by this arc were measured. Next, from the results of measurements, it was found that ; 1) as the dielectric breakdown voltage V_B increases, E (dB) increases. 2) generally, the damped oscillation appears just after the dielectric breakdown, and this oscillation is one of the main reason of radio noise.
The calculated values of power absorbed in a simulated human head exposed in the near field of portable radio transmitters are presented. A head is simulated by a homogeneous lossy sphere, and λ/2 dipole antenna is substituted for a portable radio transmitter. The distribution of the absorbed power is given for the 1Ocm radius sphere exposed in the field of 1.0W antenna power. The heating potential is 2 to 6 times higher than that exposed in the plane wave with power density of 1mW/cm^2 (the American National Standard Safety Level) at the nearest face of the sphere to the antenna.
In our previous articles, ^<(1)(2)>we proposed the delay type inductive diffusion cable for roadside vehicle radio communication, in which the electro-magnetic fields are limited in its neighborhood and do not interfere with remote radio equipment. In 1980,this cable was installed experimentary in our national route No. 17,and has attracted public attention as a new roadside information system which can be expected to attain more popular application in Japan. In this report, the detailed measurement is made for this type cable installed in the test course of the Public Works Research Institute.